Midwest Vegetable Guide - 2022 - 127

Cucurbit Crops - Diseases
off caused by Phytophthora and Pythium. Ridomil products
cannot be used until 6 weeks after transplant. REI: 48-hour.
FRAC 04.
azoxystrobin products (azoxystrobin)
Cantaloupe/Muskmelon, Cucumber, Pumpkin, Squash,
Watermelon | Use 0.83 lb. per gallon formulations (Dynasty)
for seed treatment at 0.10-0.38 fl. oz. per 100 lbs. of seed.
REI: 4-hour. PHI: 1-day. FRAC 11.
Maxim 4FS (fludioxonil) Cantaloupe/Muskmelon,
Cucumber, Pumpkin, Squash, Watermelon | 0.08-0.16 fl. oz.
per 100 lb. of seed. Seed treatment will help prevent
damping-off caused by Rhizoctonia spp. REI: 12-hour.
FRAC 12.
Previcur Flex (6) (propamocarb) Cantaloupe/Muskmelon,
Cucumber, Pumpkin, Squash, Watermelon | For Pythium in
the field, apply 0.6-1.2 pts. per acre directed to base of plant
and surrounding soil, or through drip irrigation or transplant
water. In the greenhouse, maintain a 1:1000 stock solution of
12.8 fl. oz. per 100 gals. of water. Use that stock at 3.4-6.8 fl.
oz per plant. REI: 12-hour. PHI: 2-day. FRAC 28.
Ridomil Gold SL (4SC) (mefenoxam)
Cantaloupe/Muskmelon, Cucumber, Pumpkin, Squash,
Watermelon | 1-2 pts. per acre. For use on damping-off
caused by Pythium species. Other formulations include
MetaStar, Subdue Maxx, Ultra Flourish, and Xyler. Rates
vary by formulation. REI: 48-hour. PHI: 5-day. FRAC 04.
Downy Mildew of Cucurbits -
Pseudoperonospora Oomycete
The fungus-like organism that causes downy mildew,
Pseudoperonospora cubensis, has two clades. Clade 1 occurs
more frequently on watermelon, pumpkin, and squash while
clade 2 occurs more frequently on cucumber and cantaloupe.
The pathogen does not survive Midwest winters because it
requires green, living plant tissues. That means this organism
only overwinters in south Florida or in greenhouses in
northern U.S and Canada. The wind carries downy mildew
spores to new, living hosts in the Midwest as early as July,
and sometimes not at all. Since pumpkins are grown until
relatively late in the growing season, this crop is often
affected more than other cucurbits.
Clade 2 of the pathogen can quickly become resistant to
fungicides, and some are no longer effective. Strobilurin
fungicides (such as Cabrio, Flint, Merivon, Pristine, Quadris,
Reason, Satori) and fungicides with the active ingredient
mefenoxam (such as Ridomil) are particularly prone to
resistance. In addition, Revus and Previcur Flex have
occasionally been ineffective for management of downy
mildew. In addition, Revus and Previcur Flex have
occasionally been ineffective for management of downy
mildew.
Non-Pesticide
Cantaloupe/Muskmelon, Cucumber, Pumpkin, Squash,
Watermelon | Partially-resistant varieties of cucumber and
cantaloupe are available. If your market supports it, avoid late
planted cucumbers that will yield after early July when
disease pressure is strongest.
Pesticide
Catamaran (potassium phosphite, chlorothalonil)
Cantaloupe/Muskmelon, Cucumber, Pumpkin, Squash,
Watermelon | 6 pts. per acre. REI: 12-hour. PHI: 1-day.
FRAC 33, FRAC M05.
chlorothalonil products (chlorothalonil)
Cantaloupe/Muskmelon, Cucumber, Pumpkin, Squash,
Watermelon | Several formulations of chlorothalonil (Bravo,
Echo, Equus) are labeled at various rates. See label for
directions. REI: 12-hour. PHI: 0-day. FRAC M05.
Elumin (4SC) (ethaboxam) Cantaloupe/Muskmelon,
Cucumber, Pumpkin, Squash, Watermelon | 8 fl. oz. per acre.
Tank-mixing this product with a contact fungicide such as
chlorothalonil or mancozeb will help reduce resistance
concerns. REI: 12-hour. PHI: 2-day. FRAC 22.
Forum (4.17SC) (dimethomorph) Cantaloupe/Muskmelon,
Cucumber, Pumpkin, Squash, Watermelon | 6 fl. oz. per acre.
REI: 12-hour. PHI: 0-day. FRAC 40.
Gavel 75DF (zoxamide, mancozeb)
Cantaloupe/Muskmelon, Cucumber, Pumpkin, Squash,
Watermelon | 1.5-2.0 lbs. per acre. REI: 48-hour. PHI: 5-day.
FRAC 22, FRAC M03.
mancozeb products (mancozeb) Cantaloupe/Muskmelon,
Cucumber, Pumpkin, Squash, Watermelon | Several
formulations of mancozeb products (Dithane, Manzate,
Penncozeb) are labeled at various rates. See label for
directions. REI: 24-hour. PHI: 5-day. FRAC M03.
Omega 500F (4.17) (fluazinam) Cantaloupe/Muskmelon,
Cucumber, Pumpkin, Squash, Watermelon | 0.75-1.5 pts. per
acre. REI: 12-hour. PHI: 7-day for cucumber and squash, 30day
PHI for watermelon, and cantaloupe/muskmelon. FRAC
29.
Orondis Opti Premix (SC) (oxathiapiprolin,
chlorothalonil) Cantaloupe/Muskmelon, Cucumber,
Pumpkin, Squash, Watermelon | 1.75-2.5 pts. per acre. Make
no more than 2 sequential applications before rotating to a
different mode of action. When 3 fungicide applications are
used, Orondis can be in no more than 33% of the
Midwest Veg Guide 2022
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Midwest Vegetable Guide - 2022

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